Project Wolf in Sheep's Clothing: 273 - > 408 Magnum Swap

Magnum Engine Swaps

  1. trainwreck517

    trainwreck517 Member

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    Hi All,

    Just wanted to say thanks for all the content; I am avid user of the search function which has helped me with my 1967 Barracuda project car. Now I am at a point where I should be able to contribute back to this community.

    As peppy as the 273HP engine is, it still does not give the muscle car driving experience. As a result I have decided to do a 408 engine swap using BluePrint Engines bpc4085ctcd minus Fuel and ignition systems. My intent is to dress up the 408 just like the 273 commando so that it still looks like a 273 to the untrained eye.

    Goal of this thread is to post part number used and video of the progress and modifications needed, such as modifying 273 motor mount bracket to fit the magnum block, so that it may help others.

    Here is the video of the intro and engine delivery:


    My goal is to have a new video posted every week or two showing progress / modifications / PN used in the videos.

    If there are any questions from what you see, please ask and I will try to address them as best I can.

    Thanks.
     
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    • Mopar Tim

      Mopar Tim FABO Gold Member FABO Gold Member

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      I am doing the same swap, more or less.....in a 66. Motor mounts mod is simple, I posted in the coffee thread....cool...:thumbsup:
       
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      • Mopar Tim

        Mopar Tim FABO Gold Member FABO Gold Member

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        This is going in
        1614115448629761289018777125246-jpg.jpg
        16141128879368227066411289903687-jpg.jpg Here.
        1614113537805828253975993222683-jpg.jpg
        A blue print 408, magnum based with LA Heads...
         
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        • Mopar Tim

          Mopar Tim FABO Gold Member FABO Gold Member

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          A issue will be, if you want to use the 273 air cleaner, you are very restricted to what intake you use. It is too tall with any kind of duel plane intake...IMO....At least in a early A
           
        • trainwreck517

          trainwreck517 Member

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          Looks like a nice project Tim!

          Yea, I currently run a 9in X 2in high flow filter kit (SPE-47708), with the top side of the 273 commando air cleaner covering it. This allows it to be recessed down a bit and allows for me to run a 1/2 spacer with plenty of hood clearance on the 273.. Will be a tight fit with the dual plane intake manifold on the 408, may have to modify it a bit to make it clear the hood.
           
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          • Mopar Tim

            Mopar Tim FABO Gold Member FABO Gold Member

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            Fyi a Holley sits lower than Carter...
             
          • triumphman

            triumphman FABO Gold Member FABO Gold Member

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            There are 1" dropped base air filter pans available if you need more clearance.
             
          • diymirage

            diymirage HP@idle > hondaHP@redline

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            need to put some "sheepwool blue" paint on those heads
             
          • trainwreck517

            trainwreck517 Member

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            Part 2:




            Got the engine out and did an overview of engine mount modifications for 67 273 to magnum block and transmission input shaft/drum swap to fit the 68 and newer torque converter.
             
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            • Brooks James

              Brooks James Dustoff

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              Yes Edelbrocks has one
               
            • trainwreck517

              trainwreck517 Member

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              Made progress this past weekend:



              Parts used in this video:

              Torque Strap: Mevotech MK8848 - Sway Bar Link
              7/16 heim joint RH
              3/8" 1.75" wide bar stock

              Flex Plate:
              B&M 10239 -Flex Plate
              200-2903 - ARP Flex Plate Bolts
              Torque Converter: 27-25HD - Hughes Performance Street Master Torque
              240-7302 - ARP Torque Converter Bolts

              Converter Strut Bar: QA1 52311

              Headers: D453-R - Doug's Headers D453-R

              Everything went well on the install, but now that I have the engine in I started dressing it up and ran into a few issues I wasn't aware about.
              70s and newer water pump stick out an extra 0.75", as a result the water pump pulley and crank do not align and my radiator efan w/shroud setup no longer fitting. I ordered some 360 pulleys that should resolve this, but another issue is that the heads stick out about 0.25 further than the 273. As a result my alternator (aftermarket 165A that is wider than stock) is also slightly out of alignment with the 273 crank pulley. I am hoping the 360 crank pulley sticks out a bit further than the 273, does anyone know? Otherwise I'll find out when the pulley's arrive next week. Back up plan is to use a double pulley and use the outer pulley for the alternator.



              Thanks, I ended up using Spectre Performance SPE-47708 Air Cleaner base & 2" filter with the commando top. This left me with about 0.75" of clearance between the hood and filter cover. I had to get a bit creative on the fuel line routing since they now sit within the commando filter cover, but overall looks good. Will cover this in the next video.

              IMG_20210309_1851511.jpg
               
            • triumphman

              triumphman FABO Gold Member FABO Gold Member

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              Saw your video. Looks like you and your guys are having fun.
              Re crank alignment: You may have to go to an electric fan, and by it not lining up, is normal.
              Realize some things you will find and have already found out is "Some things almost fit".
               
            • Brooks James

              Brooks James Dustoff

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              Agree it took me a while to get the balancer/flex plate/converter situation figured out on the 360 magnum. Also there was frig problems with the water pump/pulleys/ alternator/ Schumacher mounts modify . Thank God for grinders and different size washers.
               
            • trainwreck517

              trainwreck517 Member

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              Yeah, I have an electric fan setup I used with the 273, but now that the new water pump stick out an extra 0.75", it hits the fan:

              IMG_20210308_1820280.jpg

              Solution was to remove the shroud and go with a pusher setup:

              IMG_20210309_1647508.jpg

              IMG_20210309_1648089.jpg

              Need to figure out the fan mounting, as I don't want to strap it through the radiator. Bit concerned if the pusher setup will provide enough cooling or not, so will keep an eye on the gauges.


              Yea, took quite a bit of research to figure out what parts to use, so figure I'll list what worked for me to make others life easier if they decide to do a similar swap.
               
            • triumphman

              triumphman FABO Gold Member FABO Gold Member

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              I installed a/c and had to move the radiator back an inch. So I understand your issue. My car came with a/c so I found the stock rad on amazon. $150.00 less than Year One, same part #. runs at 180 @ 75mph with a/c on.
              As for yours cooling at a normal temperature (180 or so) you just have see how it does when your done.
               
            • trainwreck517

              trainwreck517 Member

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              Got the car running this weekend:



              Pully kit used: CVF Racing, Part number: SCRL1KIT

              Overall engine seems to be doing well, once I sorted out the timing and idle adjustment it fires right up.

              It's faster than before, but not Tesla fast. Granted I did shift early while just getting into the power band.

              I will do a follow up video in a few weeks, once break-in is done. Going to try to get access to a friends dyno and do some pulls on a Chassis dyno to see how much the engine puts out once installed with full exhaust and accessory restrictions.

              But overall fairly straightforward swap. Modified engine mounts, pulleys (assuming pre-70s car), transmission, flex plate and torque converter to match and drops right in place.

              Overall at 1st glance I think it achieves my objective as looking as a stock-ish 273 commando:

              IMG_20210323_0950307.jpg

              Still need to tidy up a few things, re-glue the pie tin, etc. But overall happy with the results.
               
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              • seventyswinger

                seventyswinger Well-Known Member

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                Any modifications to get a starter to work ? Which one did you use ?
                 
              • toolmanmike

                toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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                Love those Charger/Commando air cleaners but they sure don't look like they flow much. The air space between the filter and cover isn't much. Just a observation.
                 
              • trainwreck517

                trainwreck517 Member

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                I did need to grind down a boss on the block about 1/8 of an inch, I used a Powermaster 9300 but I believe any V8 mini starter will work.

                Agreed, I am using a small 2in tall high flow cotton filter but it begins to pull a slight vacuum after 4000rpms. Logs show about -0.8in at 5600rpms, so not too bad but could definitely use a larger filter. I just wanted to keep the stock factory look, so may run a different filter when I hit the drag strip and keep the chrome one on for cruising and car shows.

                Did a road trip with the car for our wedding anniversary at the end of April, car performed well. About 1 quart of oil consumption on the 1st half and no noticeable consumption the second half.

                Montage of a few clips driving up the coast of California:



                I also performed the 1st oil change and oil relocation:


                Oil looked typical for a engine break-in, no bearing material.


                Been driving it during weekends, took it to a local car show today:
                IMG_20210611_1743227.jpg

                About 700 miles on the engine now, and happy with the engine swap.
                 
                Last edited: Jun 11, 2021
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                • RustyRatRod

                  RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                  Real nice. I like the videos. You did a real good job on those. Nice job on the car, too.
                   
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                  • triumphman

                    triumphman FABO Gold Member FABO Gold Member

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                    Looks great.
                     
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